i have seen this technique many times in the 2 years ive worked the night shift at my job. bedford park pd will sit facing north, in the median, with all lights off, just at the bottom (south side) of the cicero bridge, and radar the traffic heading south over the bridge. even if you put your car in neutral at the top of the hill while going the speed limit, you will be speeding by the time you see the police car. i know because i have personally verified this in several different vehicles.